Conventionally, various types of electronic devices have been developed and widely used. Among them, as a personal computer provided with an information calculation function (hereinafter, abbreviated as PC), a portable note PC and a stationary desktop PC are widely used. In the portable note PC, an image display unit having a display screen and a main unit are coupled by means of a hinge member that fastens them so as to be freely closed and opened. The main unit incorporates such as a circuit board on which a central processing unit (CPU) for executing a program and an electronic circuit are mounted, and a hard disk in which information is stored. The main unit also serves as a keyboard with plural operational keys arranged on a top surface of the portable note PC. The stationary desktop PC includes a main device incorporating a circuit board on which a CPU for executing a program and an electronic circuit are mounted, and a hard disk in which information is stored; an image display device having a display screen for displaying an image; and a keyboard for key operation or the like, each as separate casings.
Recently, an all-in-one desktop PC has been developed and commercialized. This all-in-one type desktop PC incorporates both a main device and an image display device in one case equipped with a handle as well as a folding stand, making the all-in-one desktop PC easy to carry. A keyboard is provided on a lower portion of the case such that a rear edge of the keyboard in a using state in which the keyboard is kept with operational keys lying upward is rotatably supported. The keyboard is rotated in a direction to raise a front edge of the keyboard in the using state, between the using state and a stowed state where a display screen is partially or wholly covered by the keyboard.